Impossible to say as the base bid throws up oddities every year. Both have been traditionally closed bases IE difficult to get into, EDI only opened last year though. There's been some movement out of late so never say never. NCL is traditionally a less popular base so may be an option if you're tgat side of the country?
No, they don't do long haul but do some mid haul night stops, SSH, SID, BVC, HRG etc. Not sure what the exact status is right now though
Much touted after the bid for Summer 16 is the balancing of bases is now pretty close to what they want IE the number of UK out if base operations should be down. Again, there will be others better able to comment but GLA and EDI are probably towards the lower end for nights away. One or two a month in high summer? Honestly, don't really know.